Ebola: timeline of a ruthless killer

Following are the main developments since the worst-ever epidemic of the haemorrhagic fever Ebola emerged in west Africa earlier this year.The global death toll for the virus on Tuesday reached 1,013 out of 1,848 confirmed, suspected or probable cases, the World Health Organization said.

March 2014

22: Guinea identifies the Ebola virus as the source of a highly contagious epidemic raging through its southern forests, as the death toll rises to 59.Experts had been unable to identify the disease, whose symptoms were first observed six weeks before, but scientists studying samples in the French city of Lyon confirmed it was Ebola.

8: The WHO says the Ebola outbreak is among the "most challenging" for health workers since the deadly disease first emerged four decades ago in Zaire, now the Democratic Republic of Congo.

May

26: Sierra Leone confirms its first fatality.

June

21: The WHO says the rapid spread of Ebola in the countries concerned has occurred in part because containment efforts have been too relaxed.

July

3: The WHO says it expects the Ebola outbreak to continue for at least "several months".

25: The virus spreads to Africa's most populous country Nigeria, as a Liberian national dies in quarantine in Lagos. The country places its ports and airports on alert.

30: Doctors Without Borders warns that Ebola is out of control and there is a risk of it spreading to other countries.Liberia announces it is shutting all schools.

August

1: At a regional summit in Conakry, Sierra Leone, Guinea and Liberia announce a cross-border isolation zone around the epicentre of the outbreak.

5: The World Bank earmarks up to $200 million to help contain Ebola, as African leaders visit Washington for a US-Africa summit. The Liberian and Sierra Leonean leaders decide not to travel to the summit.

An American missionary who contracted Ebola while helping patients in Liberia arrives in Atlanta for treatment, days after a US doctor was evacuated.Both receive an experimental serum called ZMapp, which reportedly shows promising results.

8: The WHO declares the Ebola epidemic a "public health emergency of international concern".Nigeria follows Liberia and Sierra Leone in declaring a national emergency.

11: Liberia, which is promised delivery of ZMapp by the United States, puts a third province under quarantine. Eight Chinese medical workers who treated Ebola patients are placed in quarantine in Sierra Leone.

12: The WHO authorises the use of experimental drugs in the fight against Ebola, after an ethical debate. An elderly Spanish priest becomes the first European to die from Ebola in the latest outbreak, five days after being evacuated to Madrid from Liberia.